Appointment: the option to block out certain times on certain dates

It would be great if we could block out certain times on certain dates in the future. At present, it is possible to block out whole days only (under the vacations & holidays) but I want to be able to block out specific times to be unavailable.
Even better would be if it could use a Google Calendar as the basis for this (i.e. if there is a slot taken in Google calendar, then this time slot wouldn't be available in the appointment form).

Hello Mark,

That is currently not an option in the Appointment field. You can only set a limit based on the date, not date and time.

I have raised this ticket to our developers to see if they can add this in the future. We cannot provide you a timeframe of the request, but if we have updates, you will be informed here.

Thank you.